Are the Curnow versions of Maynard's charts accurate?
 
Yes, they are the real deal.  Bob Curnow is one of the few people that has been given access to do more than view the charts in Denton, and if there's a missing part or a part that never existed, such as a 3rd trombone part, he will often go straight to the composer to see what they would have written for a 3rd trombone part, etc.